Wear and abrasion resistant, high impact, iron alloy members are employed in a variety of applications, in particular, in rock crushing machines for crushing rocks and ore. A common machine used for crushing rocks is a centrifugal rock crusher, such as disclosed in U.S. Pat. No. 5,533,685.
Centrifugal rock crushing apparatus typically contain cast iron impact members called impeller shoes, which throw or propel rocks against stationary members called anvils to effect crushing of the rock. Both the impeller shoes and the anvils are subjected to repeated, high force impact loading, which of course is necessary to break apart the rocks. During operation of the rock crusher, the impact surfaces, or wear faces, of the impeller shoes receive tremendous abrasion and wear, which after even a few hours of use require replacement of the shoes. Consequently, the type of material used to fabricate the impeller shoes, as well as the anvils, is of critical importance.
Replacement of impeller shoes, as well as of anvils, requires complete shut down of the machine, in order to gain access to the impeller shoes. Shut down of the rock crusher can last for 2-4 hours, in order to remove and replace the old impellers and anvils. Consequently, rapidly wearing rock crusher components significantly increases downtime and maintenance, which adds cost to the operation. Thus, it is highly desirable to provide an iron alloy member capable of withstanding high impact yet also having increased wear resistance, particularly at the wear surface.
Cast white iron alloys are economical to produce and are widely used in the rock crushing industry. White iron alloys have been found to be one of the more impact and wear resistance of the iron alloys. However, impeller shoes made from these alloys still require frequent replacement due to significant wear and abrasion. Conventional cast white iron impellers and anvils can require replacement after as little as 6-8 hours of use. The useful life of rock crusher impellers can be longer, for example, as long as 40 hours, depending upon the material being crushed, but in every case, it would be desirable to increase the life of these critical rock crusher components. Despite there drawbacks, white iron alloy impellers and anvils are, however, still the preferred choice for use in centrifugal impact rock crushers.